Performance evaluaton of dynamic HV cables with Al conductors for floating offshore wind turbines

Abstract

Floating Offshore Wind turbine installations will require HV dynamic power cables to be connected to the longer length static export power cables. Experience from offshore wind installations has highlighted the criticality of power cables, underlining the need for high integrity, yet cost effective cable solutions. This paper will assess the mechanical performance and load parameters for an Aluminum power conductor cable. Whilst copper is the conventional choice due to its lower resistive losses, Aluminum cores are increasingly used for static power cables, due to their benefits regarding overall cable weight and material cost. The work presented adopts a coupled aero-elastic and hydrodynamic modelling approach to simulate the behavior of the well-documented OC4 semi-sub platform, together with the 5MW NREL wind turbine. The model allows a direct comparison between the two cable types, maintaining the overall system and environmental conditions. The results inform the design envelope for the ultimate load conditions. Two critical cable design parameters, the effective tension and bending radius, are quantified through global load estimates, to subsequently inform the local stress analysis. The results will form the basis for future physical demonstration and validation tests. This paper will be of interest to technology developers and practitioners concerned with submarine dynamic power cables. It offers a methodology to directly compare and evaluate different cable design options and provides some design guidance for aluminum conductor cables.